It seems necessary to understand the association of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), with its entering bronchoalveolar and brain cells, which have a high concentration of angiotensin-converting enzyme 2 (ACE2). Although the virus infects healthy people, the rate of infection and mortality is higher and significant in vulnerable people, such as drug users and addicts who have acute and chronic respiratory disease. It also places a heavy economic burden on families and societies around the world. Thus, researchers are aiming to provide prevention and treatment strategies to people at risk. The purpose of the present study was to collect studies on the rate of infection with coronavirus in people who abuse drugs. Besides, the role of the ACE2 receptor as a key factor in coronavirus infectivity in these people was investigated. Our narrative review on the relationship between COVID-19 and opioid abuse and smoking, with consideration of ACE2's role, contains original and human studies. According to the results of the current study, those who smoke or are dependent on opioids are much more likely to experience COVID-19-related respiratory side effects or even pass away.
